Quantitative near infrared tissue spectroscopy in the 650-1000nm wavelength range is a sensitive non-invasive tool for measuring tissue optical properties, and correlating them with tissue components such as water, lipids, oxy-hemoglobin, and deoxy-hemoglobin. In particular, the use of both frequency domain and steady state broadband measurements offers considerable promise in the detection, characterization, and therapeutic monitoring of breast cancer. Currently, however, obtaining accurate spectral information requires multiple discrete diode lasers and a white light source for measurements at a single source and detector position. This requires a complex and power consumptive system, with increasing complexity for multi-point measurements of spatial variation. This research seeks to create a single-chip multi-wavelength source that can replace both discrete diode lasers and white light sources. The proposed source employs wafer bonding technology to create monolithic 16-channel multi-wavelength arrays. In conjunction with temperature tuning, this source can cover the entire 650-1000nm spectrum, and be used for both frequency domain and steady state measurements. Phase ! will demonstrate feasibility with a 4 channel array. Phase II will extend to complete wavelength coverage, optimize power, and incorporate the new source into a functional spectroscopic probe which will be evaluated in tissue phantoms, animal models, and human subjects.